Harbor Real Return Fund Administrative Class (HRRRX)

Investment Strategy

Under normal market conditions, the Fund expects to invest at least 80% of its net assets, plus borrowings for investment purposes, in inflation-indexed bonds of varying maturities issued by the U.S. government, non-U.S. governments, their agencies or instrumentalities, and corporations, which may be represented by forwards or derivatives such as options, futures contracts or swap agreements. Assets not invested in inflation-indexed bonds may be invested in other types of fixed income securities.

Inflation-indexed bonds are fixed income securities that are structured to provide protection against inflation. The value of the bond's principal or the interest income paid on the bond is adjusted to track changes in an official inflation measure. The U.S. Treasury uses the Consumer Price Index for Urban Consumers as the inflation measure for U.S. Treasury Inflation-Protected Securities ("TIPS"). Inflation-indexed bonds issued by foreign governments are generally adjusted to reflect a comparable inflation index, calculated by that government. "Real return" equals total return less the estimated cost of inflation, which is typically measured by the change in an official inflation measure.

The Fund may invest up to 30% of its total assets in securities denominated in foreign currencies, and may invest beyond this limit in U.S. dollar denominated securities of foreign issuers. Foreign currency exposure (from non-U.S. dollar denominated securities or currencies) normally will be limited to 20% of the Fund's total assets. The Fund also may invest up to 10% of its total assets in securities and instruments that are economically tied to emerging market countries (this limitation does not apply to investment-grade sovereign debt denominated in the local currency with less than 1 year remaining to maturity).

The Fund may invest, without limitation, in derivative instruments, such as options, futures contracts or swap agreements (including currency swaps, interest rate swaps, total return swaps, credit default swaps and others, in which the Fund may be either the buyer or the seller), or in mortgage- or asset-backed securities, subject to applicable law and any other restrictions described in the Fund's prospectus or Statement of Additional Information. The Fund may, without limitation, seek to obtain market exposure to the securities in which it invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as buy-backs or dollar rolls). The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis and may engage in short selling, which is the sale by the Fund of a borrowed security. Because the Fund is obligated to replace the borrowed security, the Fund would benefit from the short sale if the price of the security declines before it is replaced. The Fund may also invest up to 10% of its total assets in preferred stocks.

Credit Quality. The Fund invests primarily in investment-grade debt securities, but may invest up to 10% of its total assets in below investment-grade securities, commonly referred to as "high-yield" or "junk" bonds. For all securities other than mortgage-related securities, the Fund may invest in below investment-grade securities only if they are rated B or higher by Moody's, S&P or Fitch, or, if unrated, determined to be of comparable quality. For mortgage-related securities, the Fund may invest in securities of any credit quality, including those rated below B.

Duration. The average portfolio duration of this Fund, as calculated by the Subadviser, normally varies within three years (plus or minus) of the duration of the Bloomberg Barclays U.S. TIPS Index, which as of December 31, 2017 was 7.66 years. Average duration is a weighted average of all fixed income security durations in the Fund's portfolio, and is an approximate measure of the sensitivity of the market value of the Fund's holdings to changes in interest rates. If the Fund's duration is longer than the market's duration, the Fund would be expected to experience a greater change in the value of its assets when interest rates are rising or falling than would the market as a whole. The average duration of the Fund's portfolio was 7.25 years as of December 31, 2017.

Risks

There is no guarantee that the investment objective of the Fund will be achieved. Fixed income securities fluctuate in price in response to various factors, including changes in interest rates, changes in market conditions and issuer-specific events, and the value of your investment in the Fund may go down. This means that you could lose money on your investment in the Fund or the Fund may not perform as well as other possible investments. Principal risks include:

Credit risk: The issuer or guarantor of a security owned by the Fund could default on its obligation to pay principal or interest or its credit rating could be downgraded. Likewise, a counterparty to a derivative or other contractual instrument owned by the Fund could default on its obligation. This risk may be higher for below investment-grade securities.

Currency risk: The risk that foreign currencies will decline in value relative to the U.S. dollar and affect the Fund's investments in foreign (non-U.S.) currencies or in securities that trade in, and receive revenues in, or in derivatives that provide exposure to, foreign (non-U.S.) currencies.

Derivatives risk: The value of derivative instruments held by the Fund may not change in the manner expected by the Subadviser, which could result in disproportionately large losses to the Fund. Derivativesmay also be more volatile than other instruments and may create a risk of loss greater than the amount invested. In addition, certain derivatives may be difficult to value and may be illiquid.

Emerging markets risk: The risk of investing in emerging market securities, primarily increased foreign (non-U.S.) investment risk, as well as additional risks, such as exposure to economies less diverse and mature than those of the U.S. or more established foreign markets, which can result in greater price volatility.

Equity risk: The values of equity or equity-related securities, such as preferred stocks, may decline due to general market conditions that are not specifically related to a particular company, such as real or perceived adverse economic conditions, changes in the general outlook for corporate earnings, changes in interest or currency rates or adverse investor sentiment generally. They may also decline due to factors that affect a particular industry or industries, such as labor shortages or increased production costs and competitive conditions within an industry. Equity securities generally have greater price volatility than fixed income securities.

Extension risk: When interest rates are rising, certain callable fixed income securities may be extended because of slower than expected principal payments. This would lock in a below-market interest rate, increase the security's duration and reduce the value of the security.

Foreign securities risk: Because the Fund may invest in securities of foreign issuers, an investment in the Fund is subject to special risks in addition to those of U.S. securities. These risks include heightened political and economic risks, greater volatility, currency fluctuations, higher transaction costs, delayed settlement, possible foreign controls on investment, possible sanctions by governmental bodies of other countries and less stringent investor protection and disclosure standards of foreign markets. Foreign securities are sometimes less liquid and harder to value than securities of U.S. issuers. These risks are more significant for issuers in emerging market countries. Global economies and financial markets are becoming increasingly interconnected, and conditions and events in one country, region or financial market may adversely impact issuers in a different country, region or financial market.

High portfolio turnover risk: Higher portfolio turnover may adversely affect Fund performance by increasing Fund transaction costs and may lead to the realization and distribution to shareholders of higher capital gains, which may increase a shareholder's tax liability.

High-yield risk: There is a greater risk that the Fund will lose money because it invests in below investment-grade fixed income securities and unrated securities of similar credit quality (commonly referred to as "high-yield securities" or "junk bonds"). These securities are considered speculative because they have a higher risk of issuer default, are subject to greater price volatility and may be illiquid.

Inflation-indexed bond risk: Inflation-indexed bonds may decrease in value in response to actual or anticipated changes in inflation rates in a manner unanticipated by the Fund's subadviser or investors generally. There can be no assurance that the inflation index used will accurately measure the real rate of inflation in the prices of goods and services. Inflation-indexed bonds are subject to interest rate risk, credit risk, prepayment risk and extension risk.

Interest rate risk: As interest rates rise, the values of fixed income securities held by the Fund are likely to decrease and reduce the value of the Fund's portfolio. Securities with longer durations tend to be more sensitive to changes in interest rates and are usually more volatile than securities with shorter durations. For example, a 5 year average duration generally means the price of a fixed income security will decrease in value by 5% if interest rates rise by 1%. Interest rates in the U.S. are near historic lows, which may increase the Fund's exposure to risks associated with rising rates. Additionally, rising interest rates may lead to increased redemptions, increased volatility and decreased liquidity in the fixed income markets, making it more difficult for the Fund to sell its fixed income securities when the Subadviser may wish to sell or must sell to meet redemptions.

A nominal interest rate can be described as the sum of a real interest rate and an expected inflation rate. Inflation-indexed securities, including U.S. Treasury inflation protected securities ("TIPS"), decline in value when real interest rates rise. In certain interest rate environments, such as when real interest rates are rising faster than nominal interest rates, inflation-indexed securities may experience greater losses than other fixed income securities with similar durations.

Leveraging risk: The Fund's use of certain investments, such as derivative instruments or reverse repurchase agreements, and certain transactions, such as securities purchased on a when-issued, delayed delivery or forward commitment basis, buy backs and dollar rolls, can give rise to leverage within the Fund's portfolio, which could cause the Fund's returns to be more volatile than if leverage had not been used.

Liquidity risk: A particular investment may be difficult to purchase or sell and the Fund may be unable to sell illiquid securities at an advantageous time or price or achieve its desired level of exposure to a certain sector. Liquidity risk may result from the lack of an active market, reduced number and capacity of traditional market participants to make a market in fixed income securities, and may be magnified in a rising interest rate environment or other circumstances where investor redemptions from fixed income mutual funds may be higher than normal, causing increased supply in the market due to selling activity. Valuation of investments may be difficult, particularly during periods of market volatility or reduced liquidity and for investments that trade infrequently or irregularly. In these circumstances, among others, an investment may be valued using fair value methodologies that are inherently subjective and reflect good faith judgments based on available information.

Market and issuer risk: Securities markets are volatile and can decline significantly in response to adverse market, economic, political, regulatory or other developments, which may lower the value of securities held by the Fund, sometimes rapidly or unpredictably. Additionally, an adverse event or adverse economic conditions may depress the value of a particular issuer's securities or may increase the risk that issuers will not generate sufficient cash flow to service their debt obligations.

Mortgage- and asset-backed securities risk: Mortgage and other asset-backed derivatives in the Fund's portfolio may have especially volatile prices because the embedded leverage can magnify the impact of the extension or contraction event on the underlying cash flow. Mortgage-related securities are also subject to prepayment and extension risks.

Prepayment risk: When interest rates are declining, the issuer of a fixed income security, including a pass-through security, such as a mortgage-backed or an asset-backed security, may exercise its option to prepay principal earlier than scheduled, forcing the Fund to reinvest in lower yielding securities.

Selection risk: The Subadviser's judgment about the attractiveness, value and growth potential of a particular security may be incorrect. The Subadviser potentially will be prevented from executing investment decisions at an advantageous time or price as a result of domestic or global market disruptions, particularly disruptions causing heightened market volatility and reduced market liquidity, as well as increased or changing regulations. Thus, investments that the Subadviser believes represent an attractive opportunity or in which the Fund seeks to obtain exposure may be unavailable entirely or in the specific quantities or prices sought by the Subadviser and the Fund may need to obtain the exposure through less advantageous or indirect investments or forgo the investment at the time.

Short sales risk: If the price of securities sold short increases, the Fund would be required to pay more to replace the borrowed securities than the Fund received on the sale of the securities. Because there is theoretically no limit to the amount of the increase in price of the borrowed securities, the Fund's risk of loss on a short sale is potentially unlimited.